Ethanol

THE

CHEMISTRY

AND

USES

Of

Oxygen (O2)

Ali Mousavi

11 G

Properties and bonding in oxygen

Oxygen In normal conditions is a colourless, odourless and insipid gas, oxygen is as light blue liquid when it condensates. 1

Atomic number

Atomic mass Electro negativity

Density Melting point

Boiling point

Isotopes it exists in

8 15.999 g.mol -1

3.5

1.429 kg/m3 at 20Ð'oC

-219 Ð'oC

-183 Ð'oC

3

Oxygen is a reactive element and it forms oxides with all other elements except the noble gases (helium, neon, argon, and krypton). (To be explained more in next page) 1

Oxygen is placed in group 6A in the periodic table, which means they need two more electrons to complete a stable electron octet. In this group electro negativity decreases as atomic mass increases. Oxygen is more electronegative than any element except fluorine. 1

Oxygen, bonds with itself to form 2 bonds between the atoms (since each atom needs to share 2 electrons). 3

This is the Lewis dot structure for oxygen, indicating that each oxygen atom has 4 shared electrons (2 per bond) and 4 unshared electrons; it gives each a total of 8 and fills the valence shells.3

In a case of water molecule, each water molecule consists of 2 atoms of hydrogen bonded to 1 atom of oxygen, that's why the chemical formula is like H2O. The electrons tend to spend more time around the oxygen atom than the hydrogen atoms, due to greater affinity of oxygen. This unequally shared electrons cause a dipole (partial electrical charge). 3

Due to oxygen's electro negativity, it forms chemical bonds with almost all other elements (which is the origin of the original definition of oxidation). The only elements to escape the possibility of oxidation are a few of the noble gases. The most famous of these oxides is dihydrogen oxide, or water (H2O). Other well known examples include compounds of carbon and oxygen, such as carbon dioxide (CO2), alcohols (R-OH), aldehydes, (R-CHO) and carboxylic acids (R-COOH). 9

Water is a perfect example of hydrogen bonding. Each water molecule can form 4 hydrogen bonds with other water molecules around it. There are exactly the right numbers of 8+ hydrogen and lone pairs so that every one of them can be involved in hydrogen bonding. 4

In water, dipole forces have a very strong effect to keep the molecules in a liquid state until a fairly high temperature is reached. In the graph on the bottom of the page, you can see the abnormal B.P. of H2O comparing to the other molecules in the group VI. 5

The major reason for this abnormal behavior is the strong attractions afforded by the hydrogen bonds. It takes a lot more energy in an increased temperature to break the hydrogen bonds and turn the water molecules to gas. 5

Uses of oxygen

Oxygen is famous and important for its reactivity. It has a lot of uses in steelmaking and other metals refining and fabrication processes, in chemicals, pharmaceuticals, petroleum processing, glass and ceramic manufacture, pulp and paper manufacture, healthcare, environmental protection through treatment of municipal and industrial effluents and other miscellaneous uses.6

Ð'* Industry Uses for Oxygen:

Oxygen is used with fuel gases in gas welding, gas cutting, oxygen scarfing, flame cleaning, flame hardening, and flame straightening.

In gas cutting, the oxygen must be of high quality to ensure a high cutting speed and a clean cut.

Ð'* Metals Manufacturing Uses for Oxygen:

The largest user of oxygen is the steel industry. Modern steelmaking relies heavily on the use of oxygen to enrich air and increase combustion temperatures in blast furnaces and open hearth furnaces as well as to replace coke with other combustible materials. During the steel making process, unwanted carbon combines with oxygen to form carbon oxides, which leave as gases. Oxygen is fed into the steel bath through a special lance. Oxygen is used to allow greater use of scrap metal in electric arc furnaces. Large quantities of oxygen are also used to make other metals, such as copper, lead, and zinc.

Oxygen enrichment of combustion air, or oxygen injection through lances, is used to an increasing extent in cupola furnaces, open-hearth furnaces, smelters for glass and mineral wool, and lime and cement kilns, to enhance their capacity and reduce energy requirements. Smelting times and energy consumption can also be reduced by special oxy-oil or oxy-gas burners in electro-steel furnaces and induction smelters for aluminum. A high thermal efficiency is achieved by these "oxy-fuel" burners, which mix fuel and oxygen at the tip of the burner. As a result, rapid combustion occurs at approximately 2800o C (5072oF).

Ð'* Chemicals, Pharmaceuticals and Petroleum Uses:

Oxygen is used as a raw material in many oxidation processes, including the manufacture of ethylene oxide, propylene oxide, synthesis gas using partial oxidation of a wide range of hydrocarbons, ethylene dichloride, hydrogen peroxide, nitric acid and vinyl chloride

Very large quantities of oxygen are used in coal gasification Ð'-- to generate a synthesis gas that can be used as a chemical feedstock or precursor for more easily- transported and easily-used fuels.

Oxygen is used to enrich the air feed to catalytic cracking regenerators, which increases capacity of the units. It is used in sulfur recovery units to achieve similar benefits. Oxygen is also used to regenerate catalysts in refineries.

Oxygen is used to achieve more complete combustion and destruction